Bizarre parosteal osteochondromatous proliferation of bone.

A 47-year-old man presented with a painless mass of 7 months' duration, on the plantar aspect of the great toe of the right foot. Radiographs and CT images initially suggested an osteochondroma arising from the proximal phalanx of the great toe but there was no continuity between the medullary canal of the phalanx and the lesion. The mass was excised and a histological diagnosis of bizarre parosteal osteochondromatous proliferation of bone (Nora's disease) was made. The aggressive growth of this lesion may clinically suggest a neoplasm. Histological features, however, are those of a reactive lesion.